环境激励下结构模态参数识别方法综述

自动获取运行中的模态参数对于大型土木结构的健康状态实时在线监测具有重要意义。针对现有方法模态分辨困难的问题，提出了一种基于解析二阶盲辨识的工作模态分析方法，并相应提出了真假模态区分方法以实现模态参数自动识别。与传统方法不同，该方法无需引入稳定图，可直接从结构振动响应中有效分离出各阶模态响应。通过构造模态特征指标和K均值聚类实现真假模态自动区分，并采用频域参数拟合法估计模态参数。通过8自由度数值算例和混凝土重力拱坝工程实例对该文方法效果进行了验证。结果表明：该方法具有较好的模态自动分离和筛选能力，对固有频率、阻尼比和振型的识别精度均较高，尤其对于密集模态的识别具有显著优势。

A review of structure modal identification methods through ambient excitation

The automated extraction of operational modal parameters is of great importance to real-time health monitoring of large infrastructures. Regarding to the shortage of the existing methods in view of the difficulty of modes discrimination, an operational modal analysis method based on analytic second-order blind identification is proposed. A companion method to discriminate between physical and spurious modes for automated identification is also developed. Unlike traditional methods, the modal responses of each mode can be separated directly from structural vibration responses without using stabilization diagrams. Physical and spurious modes can be discriminated by introducing modal metrics and adopting K-means clustering. Modal parameters can then be estimated by the frequency domain parameter fitting method. The proposed method is validated by a numerical example of 8-DOF system and an engineering example of concrete arch-gravity dam. The results show that the method has preferable ability in automated modes separation and discrimination and, demonstrates high precision in the identification of natural frequencies, of damping ratios and, of mode shapes, showing remarkable advantages, especially in the appearance of closely spaced modes.